Civil Service Exam Reviewer · Averages · hard
The average of 11 numbers is 25. The average of the first 6 is 25, and the average of the last 6 is 21. What is the middle (6th) number?
- 25
- 23
- 1
- 7
Answer
C. 1
Solution
First 6 sum = 150; last 6 sum = 126. Together they count the middle number twice: 276 − 275 = 1.
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